Hydraulic control systems are in widespread use in controlling the operation of excavating equipment, hoists, lifting arms and a number of similar devices. The control systems used therein typically include control valves in the form of a spool slidable within a bore, the position of the spool determining which of a pair of outlet ports is connected to relatively high pressure fluid and which is connected to a low pressure at any given time.
More recently, twin spool control valves have been used. Such arrangements have several advantages over single spool arrangements as the positions occupied by the two spools can be controlled individually. However, the control schemes typically used to drive such control valves are very similar to those that have been used successfully in relation to the single spool arrangements.
It is an object of the invention to provide a control arrangement for such a control valve which permits enhanced performance of a device control using the control valve.